add strings for documented values of water_source for Hydrants

and drop the default value "main" (just because it's the most common value does not mean we can assume it is valid for every hydrant)

data/fields/water_source.json

@@ -1,6 +1,14 @@
 {
     "key": "water_source",
-    "default": "main",
     "type": "combo",
-    "label": "Water Source"
+    "label": "Water Source",
+    "strings": {
+        "options": {
+            "main": "Water Distribution Pipe",
+            "water_tank": "Water Tank",
+            "pond": "Pond",
+            "river": "River",
+            "stream": "Stream"
+        }
+    }
 }

interim/source_strings.yaml

@@ -4261,6 +4261,17 @@ en:
       water_source:
         # water_source=*
         label: Water Source
+        options:
+          # water_source=main
+          main: Water Distribution Pipe
+          # water_source=pond
+          pond: Pond
+          # water_source=river
+          river: River
+          # water_source=stream
+          stream: Stream
+          # water_source=water_tank
+          water_tank: Water Tank
       water_tank/volume:
         # water_tank:volume=*
         label: Volume (Liters)